Production of bitumen



Patented May 10, 1938 uirso STATES are PRODUCTION OF BITUMEN Kernel Kell, Dortmund, Germany No Drawing. Application August 24, 1934, Se

rial No. 741,296. 1933 Claims.

were caused by the ever increasing speed of the vehicles and the resultant continually increased strain on the road covering, which manifested itself in the more exacting conditions placed on the matrices which are employed in the making of these road coverings. These conditions, however, must be fulfilled so that the road maker can give without danger the exacting guaranties required of him.

Exhaustive tests have proved that the parafiin content of the bitumen is of particular importance in this respect, because the most valuable properties of this product, for example, its elasticity and lack of sensitivity to cold, are unfavorably influenced by its paraffin content. Owing to this fact, most of the German, Polish,

Roumanian, Russian and other petroleum bitumens are not used for road making, because the deposits of petroleum in these countries contain more or less paraffin. Consequently these petroleum bitumens are regarded as of inferior quality, which is shown economically by low prices which are 20 to 50% below the market value of the Mexican or Venezuelan asphalts which are free from paraffin.

Considering that the demand for petroleum bitumen continually increases, that asphaltic petroleum free from parafiin amounts to scarcely 10% of the world production of petroleum and that, moreover, the production of the most val- '40 uable asphaltic Mexican oil has dropped by about 60% during the last three years, it must be reckoned that soon no high quality bitumen will be available for the industry. Consequently, it is of great importance to discover a process which enables the deparaflination of crude oils, residues and oils containing parafiin and. asphalt.

The removal of crystalline parafiin from distilled paraffin oils by cooling and sweating proc esses has been known for a long time. Parafiin oils and residues free from asphalt can be deparafiinated by employing various selective solvents, or by the addition of strongly crystalline organic compounds, or by centrifuging.

Hitherto, however, it was not possible to deparaffinate crude oils, residues and oils containing asphalt.

In has been unexpectedly discovered that vari ous organic solvents, which generally separate the soft and the hard asphalts from crude oils and residues containing asphalt and paraffin (so In Germany December 4,

(Cl. BBS-13) that any filtration or separation of the asphalt from the paraffin becomes impossible) serve as solvents for the soft asphalt even at low temperatures, if the petroleum residues fulfil certain requirements, or if such sharply fractionated liquid organic compounds are employed which behave as solvents only within certain limits of purity but which otherwise act as precipitants with regard to soft asphalts and therefore are unsuited for the above mentioned purpose. The unsuitability of such solvents causing a precipitation of the soft asphalts is connected with the clogging of the pores of the filter, since thereby all filtration is stopped or rendered impossible.

However, the hard asphalts behave differently from the soft asphalts.

The hard asphalts, that is to say, the bodies which can be precipitated by standard benzine,

are not always of smeary consistency. They can be precipitated by certain precipitants and under certain conditions in granular state, and they then produce porous layers in filters which do not impede the filtration. Their removal, which takes place at the same time as the deparaffination and under similar conditions, considerably improves the properties of the crude oils or residue deparafiinated according to the new method, because these are also rendered available for preparing axle oils and cylinder oils which must not contain any hard asphalt.

Thus, in an unexpected manner a double object is attained by the employment of the new process. The crude oils containing paraffin and hard and soft asphalt, and oils or residues containing paraflin and hard and soft asphalt are deparaflinated and at the same time freed from the hard asphalt (asphalt precipitated by standard benzine), so that their subsequent distillation yields low congealing lubricating oils and a first-class asphalt (soft asphalt) conforming with standards. The residues deparafunated according to the invention may be employed also for preparing axle oil and cylinder oil, for which Thus, when employing acetic ether, only the benzine will be distilled off or thicker residues will have to be again diluted by addition of kerosene or gas oil, in order to be able to deparaflin them at temperatures below -10 C. without precipitation of the soft asphalt. The

addition of acetic ether to the oil may be, for example, in the proportion of 1:1 to 1.5:1. If larger quantities are added precipitation of the soft asphalt may take place.

When employing higher homologues, such as ethyl propionate, 50 to 70% residues of crude oils freed from benzine, kerosene, gas oil or even from light oils can be treated, the proportion between solvent and oil being, for example, 1.521 to 2.5:1. Even with relatively little cooling, for example to l C. and with a cooling room temperature of about C., heavy engine oils are obtained, after filtration, distillation and re fining, which have congealing points below l0 (3.; and instead of a dull brittle asphalt, a bright ductile bitumen, which is also very suitable for preparing bitumen emulsions, is obtained. The following esters and ethers may be used, instead of acetic ether (ethyl acetate), for mixing with the crude oil which has oeen previously treated as described above: simple and mixed ethers from the series of methane, ethane, propane and so forth, such as ethyl ether, di-isopropyl ether, isoamyl ether, methyl-amyl ether and so forth;

the esters of methyl alcohol, ethyl alcohol, normal propyl and iso-propyl alcohol, of the butyl alcohols, amyl alcohols and so forth with fatty acids, such as formic, acetic, propionic, butyric and capric acid, for example, ethyl formate, amyl formate, butyl acetate.

As the employed paraffin containing crude oils or residues are good absorbents for the solvents in question, not more than 0.1 to 1% of solvent will be lost, when employing vacuum filters connected with absorption vessels containing residues containing paraffin or oils, so that economy in the practice of the process is ensured.

Another very important point in connection with the process is that the porosity of the filter surfaces is preserved by the granular consistency of the precipitated paraffin and hard asphalt, so that with proper treatment, even in the case of crude oils which contain non-crystalline paraffin, such as for example the Nienhagen crude oil (Hannover), filtration rates of 290 to 400 litres per square metre per hour and over are obtainable, so that the deparafiination apparatus is considerably reduced in extent and simplified.

The paraffin scales obtained, which also contain the precipitated hard asphalt and which generally have a congealing point of approximately 50 C. or more, can be employed as crude wax, ozocerite, crude ceresin or, after previous refining or redistillation or separation from the hard asphalt, can be worked up by selective solvents to ceresin or parafiin, whereby it is possible to obtain products having a congealing point of 65 to 70 C.

It is particularly pointed out that Landsberg (German Patent No. 2 ll,528) has already described ethyl acetate and homologues as solvents for the deparaflination of oils, but expressly for oils and residues which are free from asphalt. (See page 1, lines 1 to 17 and page 2 lines 33 and 34.) The process according to the present invention relates expressly to the treatment of crude oils and residues which contain hard and soft asphalt and paraihn, and to the obtention of asphalts free from paraffin from oils containing paraffin and hard and soft asphalt, of which nothing is mentioned or even hinted at in the aforementioned patent.

I claim:

1. Process for treating a hydrocarbon oil containing paraffin and hard and soft asphalt in order to separate paraflin and hard asphalt together therefrom'and to leave soft asphalt in the oil, which process comprises subjecting a mixture containingthe said hydrocarbon oil and a material of the group consistin of normally liquid aliphatic esters of fatty acids and aliphatic ethers to chilling to cause the precipitation of paraffin and hard asphalt together, and separating the liquid containing hydrocarbon oil and soft asphalt from precipitated parafiin and hard asphalt.

2. Process for treating a hydrocarbon oil containing paraffin and hard and soft asphalt in order to separate paraffin and hard asphalt to gether therefrom and to ave soft asphalt in the oil, which process comprises subjecting a mixture containing the said hydrocarbon oil and a material of the group consisting of normally liquid aliphatic esters of fatty c ds and aliphatic ethers to chilling to cause we precipitation of paraffin and hard asphalt together, the said material being used in such proportion in relation to the oil treated that soft asphalt is held solution while hard asphalt is precipitated ith paraffin, and separating the liquid containing hydrocarbon oil and soft asphalt from the precipitated paraffin and hard asphalt.

3. Process for treating a hydrocarbon oil containing paraffin and hard and soft asphalt in order to separate paraffin and hard asphalt together therefrom and to leave soft asphalt in the oil, which process comprises subjecting a mixture of said hydrocarbon oil. with a material selected from the group consisting of aliphatic ethers and aliphatic esters of fatty to chilling to cause the precipitation of substantially all the parafiin with hard asphalt while retaining the soft asphalt in solution in the mixture, and separating the liquid containing hydrocarbon oil and the soft asphalt from the precipitated paraffin and hard asphalt.

4.. Process for treating a hydrocarbon oil containing paraffin and hard and soft asphalt in order to separate paraffin and hard asphalt together th refrom and to leave soft asphalt in the oil, which process comprises subjecting a mixture of said hydrocarbon oil with a material selected from the group consisting of aliphatic ethers and aliphatic esters of fatty acids to chilling to cause the precipitation of substantially all the paraffin with hard asphalt, the said material being used in such proportion in relation to the oil treated that the soft asphalt is held in solution While hard asphalt is precipitated with the parafiin, and separating the liquid containing hydrocarbon oil and soft asphalt from the precipitated paraffin and hard asphalt.

5. Process for treating a hydrocarbon oil containing paraffin and hard and soft asphalt in order to separate paraffin and hard asphalt together therefrom and to leave soft asphalt in the oil, which process comprises subjecting a mixture containing the said hydrocarbon oil and a normally liquid aliphatic ester of a fatty acid to chilling to cause the pr cipitation of paraffin with hard asphalt, the said ester being used in such proportion in relation to the oil treated that the soft asphalt is held in solution while hard asphalt is precipitated with paraffin, and separating the liquid containing hydrocarbon oil and soft asphalt from the pr cipitated paraffin and hard asphalt.

KORNEL KELL. 

